Lecture 6 Flashcards
(20 cards)
How do endodontic root fillers work with radiopacity?
Requires very dense material
What is radiopacity and why is it important?
x-ray visibility dependent on physical density, atomic number etc.
want to show good contrast with other structures
What does baghdadite do?
increase bioactivity and toughness
What are some fibre-reinforced composites?
Plaster casts (glass or fibres)
External fixators
bone screws
What are some features of diamond-like carbon (DLC)?
albumin binds to it
very hard material
delamination
bad for wear components as they are too hard
How does carbon coating on metals work? What features are necessary?
coated with DLC or titanium nitride
improves blood compatibility
needs to be bioinert, wear resistant, chemically inert etc.
What is the purpose of coating microelectrodes?
prevents fibrous tissue formation around the electrode as this can impede of electrical function
What is the purpose of coating stents?
aims to prevent restenosis
What are some features of drug eluting polymers?
release via diffusion or degredation
can be controlled by several factors
used to support stents or valves
Can you use titanium for coatings?
Yes - plasma vapour of titanium or grit blast with alumina
Compare thickness of plasma spray vs physical vapour vs chemical vs electrophoretic deposition
plasma spray = thickest (up to 5mm)
physical vapour = thinnest (<1um)
chemical (sol-gel) = <10um
electrophoretic = 20-30um
What are some features of electrophoretic deposition?
Relies on movement in electric field
nano-HA is + charged in ethanol
controllable thickness
What is the optimum thickness for deposition?
50-100um
What are some features of chemical deposition of HA?
chemical process
forms thickness of < 10um
useful for complex shapes and porous surfaces
What are some features of physical vapour deposition of HA?
release by exaporating or sputtering
typically slower
less delamination
<1um thickness
Are bioactive glasses coated with HA?
Yes - HA or surface roughened
What are some features of plasma spray deposition?
MOST common and can do high rates
melts and sprays via plasma
high resorbability and poor bonding strength between HA and titanium
What do coatings do?
Help bind to the surrounding tissue to prevent loosening material which can float and damage surrounding tissue
What would you incorporate into a polymer to increase radiopacity?
Zirconia
Why are DLCs not prefered?
Difficult to attach to underlying surface
